*{
    box-sizing: border-box;
}
html,body{
    height: 100%;
}
body{
    margin: 0;
    background-image: radial-gradient(ellipse, #bbb, #666, #333);
}
#nav{
    height: 10vh;
    background-color: cornflowerblue;
    padding-top: 0.5vh;
    z-index: 1000;
}
#nav div{
    text-align: center;
    height: 5vh;
    font-size: 4vh;
    color: white;
    margin: 2.5vh auto;
    letter-spacing: 0.5vw;
}